https://www.askmehelpdesk.com/plumbing/tub-rough-question-unfinished-basement-7809.html

I would like to continue on with a fairly similar discussion from this thread. I'm about to begin building a full bathroom in my basement (on concrete) and have been trying to gather as much info as possible. The scariest thing for me is tearing up the concrete and making sure I don't make a mistake with the plumbing rough-in. I'll be building a 5x8 bathroom with vanity, toilet, and tub on left 8' wall. I'm starting with nothing. I have an open space, with a soil stack right in the way of where the door will be going (the stack runs to a first floor half bath which I'll be removing to open my kitchen up more). So the stack will be cut out and I'll be tapping into that sewer line, but running my own venting pipes (as I think the venting was done through the soil stack as is now). That's a short summary of the project.

Speedball was very helpful with some dimensional information. He stated 1' 5/8" from front wall of tub on center and 15' 1/2" from side wall on center was standard rough in for a tub (assumin 32" tub).

First question is, how accurate do you have to be with those dimensions?

Second, the dimensions above were to locate the 2" drain pipe directly beneath where the drain hole will fit. Does the drain PVC pipe coming out of the concrete need to be cut so that it measures flush with the concrete surface?

What about the overfill tube? How does that get roughed in? What would the dimensions be here, or do I need to just tee off the P-trap somehow and run PVC sideways and up to the overfill? I'm having trouble picturing it.

Do I need to cut a 1' square boxout (or dapout, whatever it's called) so that I can work in this area and not refill it?

I would really appreciate the help.

Dave


Also just to add, I don't really understand either how I will be able to make the connections at the tub drain when I won't be able to get underneath (like I could with a first floor tub, from the basement). How does that work?

Before Speedball pops in...

1. Speedball was very helpful with some dimensional information. He stated 1' 5/8" from front wall of tub on center and 15' 1/2" from side wall on center was standard rough in for a tub (assumin 32" tub).

First question is, how accurate do you have to be with those dimensions?

Today's standard tubs, like Kohler Villager, have drains 14 1/2" on center from side wall. The overflow assembly then runs right by the mud-plate. I would suggest that you just run pipe into that general location, leave it longer and cap it. Best is when you put San T about 12" to the side and run "dirt arm: diagonally to the drain location. When you are ready to set the tub, you will first install tub overflow on the tub, set the tub - and then cut off the drain pipe as needed, install trap and connect Rough-In plumbing with Overflow assembly drain with Flexible rubber coupling. f

2. What about the overfill tube? How does that get roughed in? What would the dimensions be here, or do I need to just tee off the P-trap somehow and run PVC sideways and up to the overfill? I'm having trouble picturing it.

Overflow assembly will come complete in one package. You just install it. No need to build it yourself.

3. Do I need to cut a 1' square boxout (or dapout, whatever it's called) so that I can work in this area and not refill it?

Yes, cut out 12" square box in drain area. Excavate about 8-12" deep to accommodate new trap installation.

Don't forget to put in 14"x 14" access door on the wall, behind the drain and below the faucet. You will be using that service door to connect the drain.

4. Second, the dimensions above were to locate the 2" drain pipe directly beneath where the drain hole will fit. Does the drain PVC pipe coming out of the concrete need to be cut so that it measures flush with the concrete surface?

I don't think I understand this part of your post. The best is if pipe comes into dap out from the side.

Welcome back Dave,

First question is, how accurate do you have to be with those dimensions? You'll have a little "wiggle roon" both from the trap and the tub but try to s Hang in there Davetay as close as you can, BTY, The front measure is 1 1/2"om then front plate .

Second, the dimensions above were to locate the 2" drain pipe directly beneath where the drain hole will fit. Does the drain PVC pipe coming out of the concrete need to be cut so that it measures flush with the concrete surface?
For openers that 2" raiaser wll b e coming out of a 12 X 12 tub dapout. The reason for this is that the connection betweer the tub waste and the trap raiser is made undser the flooir line in the dap out.

What about the overfill tube? How does that get roughed in? What would the dimensions be here, or do I need to just tee off the P-trap somehow and run PVC sideways and up to the overfill? I'm having trouble picturing it. You mean the tub waste and oiverflow, (see image) Don't worry! The assembly can only be mounted on the tub in one way.


The tub dap out( see image) mustb be opoen for the trap and raiserv to be connected . After it tests out you may fill it with gravel . I wouldn't cement it. You might wish to service it inn the future.

You jackhammer up the cement and trench from the main to your group, You will then wye or combo off the main and pipe over to pick up your bathroom group which should go down like this. (see image). More questions? I'm as close as a click, Tom

Nice visuals, Tom !

It's coming, but I'm still not sure yet! Haha

Ok, I will definitely not cement the dapout. Yay, I get that!

I also understand the basic drawing with red.

In the actual picture with the tub plumbing showing in the concrete there, where EXACTLY is the P-trap? Is the pipe coming up to the overflow coming directly off the U of the Ptrap? I'm just having trouble visualizing where the trap is exactly in that picture. The other PVC coming out that looks like it's a vent (yes?), that must be beyond the P-trap?

So let me see if I can explain the layout going on in the concrete below that toilet (the first diagram there is throwing me a bit because that appears to be more like the setup of my first floor tub, and what's throwing me there is the soil stack runs vertical in that case, where in the concrete the main line is running horizontal in the concrete...

Ok, so in that actual tub picture, the overflow tube is coming up from the U part of the P trap, and the horizontal (arm part of P trap) is running over underneath the 2" drain, then I have a riser there? Am I accurate so far?

How does the vent pipe in the picture (if that's what it is and appears to be) get worked in? Is it teed' off the main line I run from the sewer line?

I'm sorry guys. I'm good with the sink and the toilet, but the tub plumbing has me worried. Thanks so much for the help.


I replied before I left for work this morning, and all the way here kept thinking what I stated about running form the P-trap couldn't be the case.

Let me try again: Would the overflow tube connect and feed into the U of the P-trap, with the horizontal arm going to the sewer line, and a Tee put on just past the U to run a horionontal arm over to the Drain? Does that make more sense?

And if that's the case, it seems that there would not be quite enough room to accomplish adding a tee where the overflow tube comes out of the U and running that over to the drain.

Please stop me if I'm getting this more convoluted!

The bathroom layout that I wish to do is something like this, except that from the doorway, all fixtures are on the left wall. The sewer line I have to tap into runs parallel with the door way, right at the door way.

Hope that helps.

You don't have to put the ptrap in before you pour the concrete because of the dap box. Stub the tub drain into this box area, pour your floor back(of course not in the boxed out area. Then when you have your tub, you can put the waste and overflow on it and set the tub in place temporarily. Measure where the vertical riser of the trap needs to come out of the floor, pull the tub back out and then install the trap and riser. Now reset the tub permanently.

I'm getting there, I'm getting there.

Chayn, the picture above from Speedball showing the tub in the concrete, the overflow tube looks concreted in. I don't see a dapout box.

I guess, where will the dapout box be exactly? Is it supposed to be where the overflow tube comes out and extend to the drain as well, so ALL of that can be accessed?

Also, where exactly will the P-trap be.

"Measure where hte vertical riser of the trap needs to come out of the floor"... I take that to mean the pipe coming up directly from the U of the P-trap, which will connect to the drain on the bottom of the tub, is that right?

So really, all I'd need is the horizontal pipe in to a point that I can access it through the dapout, and later do all my measuring/connecting after the concrete is poured back?

Still not sure yet how the overflow will be able to be added later either... because the overflow tube also has to come before the P-trap, right? So how is that all going to fit?


I just re-read the post by Milo and looked at his drawing. Is the yellow square the dapout box? If so, then it makes a lot more sense now. But, it does not seem like I'd have access to the P-trap... and also, it still shows a vertical drain line (I know, but because I'm a newbie that throws me off), so really the arm of the P trap will be San T'd to the main line correct? Still seems like I'd want the dapout box over the P-trap area too, to acess, and also doesn't seem like I'd have enough depth to get a 1/4" per foot run. Seems like the 2" trap will be set deep based on the drawing (am I just reading too much into it?)

The shower will be about 8 feet (probably no more than that) from the sewage line and so I will need a 2" raise (or I guess 1" if necessary) to make it right.

Am I getting closer to understanding this? Sorry for all the posts, I'm just trying to think through it.

The dapout box is going to be placed on the drain end of the tub and centered from side to side so that you have room to put in the tub waste and overflow(which is the drain that connects to the tub) and have access to install the ptrap where it needs to be to hook to the waste and oveflow. As far as where the ptrap goes the best advice I can give is to put the waste and overflow on the tub, dry fit the tub in place, measure where the drain needs to be and then you got it. Tubs vary as to their exact center so I cannot give you a measurement.
So yes all you need before you pour is the horizontal drain coming into the dapout area so you can access it later to install the ptrap.
If you look at Speedballs image the overflow tees into the drain. It is part of the waste and overflow. Perhaps you should go and purchase one and then you will see how it goes.
The yellow part of Milos image represents the tub itself. The blue lines represent the waste and overflow and the black is the ptrap and drain and vent lines.

I think I'm getting it now. I was thinking the 12x12 dapout was only going to allow me to access where the bath drain shoe attaches to the tub. I was apparently wrong. So, I will need to make sure the dapout allows me to attach the P-trap, the waste and overflow set, and go from there. I think I got it now guys.

What's going to help is when I go and purchase all of the plumbing that will be running through the concrete. I can then piece it like a puzzle and it'll probably make sense then.

It's tough to visualize everything in your head before you've ever done it.

Thanks a lot.

I have one other concern, and that is the direction that the plumbing will be coming in for the tub, but I will ask that question after I start putting the puzzle together if it isn't working.

Thank you very much for the help.

Dap-out opening in the concrete allows you to put in trap and to connect drain after the tub is set in place. It will be all covered with tub so it will never be visible. Speedball's photo shows dap-out filled with light concrete. I personally don't think it is a preferable method - but some people do it. We always leave our dap-out boxes open so the trap and tub overflow are exposed and servicable.

Here's a better picture of a Tub Dap Out.

Speedball, THAT is the pic I needed to see. Thank you all very much.

PS. I wanted to TIP all of you who helped but I do not see the "agree/disagree" when I click on your profile.

I you wish to leave a Tip simply click on MY Profile and follow directions. Thanks for asking. Tom

Speedball,

With reference to your diagram in red:

The connection to the tub would not be able to be made with a dapout box in concrete that would allow you free access to the P-trap and overflow, would it? For instance, please see my attached diagram. This is my set up. Sink first on left, toilet in mid left, then tub as shown. My soil stack is in the middle of the room, and that is what I will be removing, as it feeds a first floor 1/2 bathroom that I will be removing to open up the kitchen.
I have to ask another question.

Can I ask for input on how you guys would route the plumbing beneath the concrete in this case? The soil stack appears to be the end of a main line, which runs back toward the door and out the room, and probably ties with another main line on the other side of the house, then runs out to the street (just a guess).

I was planning to cut up the concrete a bit south of the soil stack, then put in a san Tee over to the sink. I was going to use fernco couplers to go from where the stack is, directly to the toilet, then continue on to the tub. This will not allow me to come in from the side of the tub. I would probably then have to compensate and put Ptrap in line and come striaght up to the overflow and waste setup.

Is this how you would recommend doing the plumbing?

I am starting to feel very overwhelmed. I get nervous when I don't have experience with something, and I'm afraid I'm going to mess up my house. Don't want to pay a few grand either just to get the bathroom roughed in. I might as well not do a new bathroom at that point.

I was going to attach a pic but could not get it small enough.

Speedball's photo shows dap-out filled with light concrete. I personally don't think it is a preferable method - but some people do it. We always leave our dap-out boxes open so the trap and tub overflow are exposed and servicable.
I live in Florida where when have a subterranean termite problem.
Some of our contracts call for the dap out to be coated,( not filled) with roof cement in the case of PVC drainage or hot tar if the drainage was cast iron. Cheers, Tom

Milo:

You mentioned an access panel earlier in this thread -- Is that a personal preference or a code requirement in your area?

Also, FYI the Governing Parties behind the UPC are mulling over the idea of requiring some sort of means of sealing the buck-outs for trap/Waste and Overflows for pest/rodent control.

Mastic for buck-outs in concrete pours and wire mesh for buck-outs above grade was the last word I heard.